The present invention relates to apparatus for controlling at least one variable characteristic of a rotating element.
A simple, inexpensive, and reliable system for controlling variable characteristics of a rotating element is clearly needed. For example, it is desirable to change the pitch of an aircraft propeller to obtain high, low, flat, reverse, or feathered pitch. It is also desirable to adjust rotating elements in the oil industry (drill bit control), in the turbine engine industry (blade pitch control), and the ship and boating industry (propeller pitch control). The prior art control systems have used electrical slip rings, mechanical, and hydraulic equipment that has the disadvantage of being complicated, heavy, and/or expensive.
An aircraft propeller should have a different degree of pitch for different operating conditions. On take off a low degree of pitch is required to gain speed quickly and to climb to altitude. The propeller should then be adjusted to a high degree of pitch to obtain maximum speed. The prior art systems have not provided a reliable and inexpensive propeller pitch control system and many airplanes have had to use a fixed pitch propeller. The pitch of a fixed pitch propeller is generally chosen in the medium pitch range. This results in the aircraft operating at less than optimum performance substantially all of the time.